The death of a worker at Netmarble's game development subsidiary Netmarble Neo last year was due to excessive work, Rep. Lee Jeong-mi said Thursday.

This is the first case in which a Netmarble employee's death has been recognized as being work-related. Two other deaths occurred in 2016.

According to Rep. Lee of the Justice Party, the Korea Workers' Compensation and Welfare Service acknowledged the employee's death as work-related in June, approving the bereaved family's filing for compensation.

The employee, who was in charge of developing games, died of coronary arteriosclerosis last November.

Documents from the workers' compensation agency said the employee "died from a work-related cause, based on examination of the worker's age, type of work, working environment and other documents."

"The employee had been subject to irregular night-time work and excess duty in the 12 weeks before he developed the symptoms and it has been confirmed that the employee had worked 89 hours a week in seven weeks prior to developing symptoms," the documents stated.

"Considering the worker was in his 20s and that his health checkup did not show any underlying symptoms, the correlation between the worker's death and work is recognized."

Even on the day the employee died, which was a Sunday, he was set to go to work, according to his family members.

The employee's death publicized a widespread practice in the IT industry known as "crunch mode" which refers to employees engaging in extensive hours of labor ahead of a new launch or update, eating and sleeping at the office.

"The worker was continuously subjected to excessive labor since he started working at Netmarble Neo in 2013," said Choi Min, a medical expert in job environment at the Korea Institute of Labor and Safety.

"This indicates the possibility that not only current employees but also former employees there may have had or currently have health problems."

Rep. Lee is calling for a government investigation into two other cases of Netmarble employee deaths in 2016, on whether they occurred from overwork. She is also seeking a health diagnosis and epidemiological investigation of cardiovascular diseases developed by Netmarble employees in the past five years as well as an investigation into diseases caused by overwork among former Netmarble employees and the establishment of measures to prevent overwork.

"Companies must halt the practice of crunch mode," Lee said, urging a crackdown by the labor ministry.